Tubesheet for hollow fiber type, high temperature battery cells

Abstract

A small amount of SiO 2 is added to the sodium borate solder glasses of the type previously used to make tubesheets in hollow fiber, high temperature battery cells. The modified glass is more easily ground and has a lower softening temperature. When the powdered glass is fused, to form the tubesheet and sealingly engage the fibers, the fiber-weakening fluxing action of the glass is considerably reduced.

What is claimed is: 
     
       1. A tubesheet/hollow fiber assembly comprising a wall member with which a plurality of hollow fiber lengths passing therethrough are engaged, said wall member consisting essentially of a glass having the composition Na 2  O, from about 1 to about 6.1 mole %;   SiO 2 , from about 2.5 to about 7.5 mole %; and   B 2  O 3 , from about 86.5 to about 96.5 mole %; and     said fibers being composed of a ceramic which has a distortion temperature higher than the fusion temperature of said glass,   has a thermal coefficient of expansion which within the range from 25° C. up to its transistion temperature--does not differ from that of said glass by more than 10×10 -7  units/°C., and   is capable of sealingly bonding with said glass at said fusion temperature without being fluxed by the glass to such an extent that the flex strength of said fibers is reduced by more than 50%.     
     
     
       2. An assembly as in claim 1 in which the walls of said fibers are ion-permeable. 
     
     
       3. An assembly as in claim 2 wherein said ions are cations of an alkali metal. 
     
     
       4. The assembly of claim 3 in which said alkali metal is sodium and said fibers have a distortion temperature of at least 340° C., a coefficient of thermal expansion within the range of from about 100 to about 130×10 -7  units/°C. and an electrical conductivity of at least 5×10 -5  ohm cm at a temperature within the range of from about 280° C. to about 325° C. 
     
     
       5. An assembly as in claim 4 in which said fibers consist essentially of a ceramic having the composition: Na 2  O  25-34 mole %   B 2  O 3   50-60 mole %   SiO 2   0-11 mole %   NaCl  0-6 mole %.   
     
     
       6. An assembly as in claim 5 wherein said ceramic has the composition: Na 2  O  29.0-30.5 mole %   B 2  O 3   58-60 mole %   SiO 2   5.5-6.5 mole %   NaCl  4.5-5.5 mole %.   
     
     
       7. An assembly as in claim 6 wherein said ceramic has the composition: Na 2  O about 29.8 mole %   B 2  O 3  about 59.5 mole %   SiO 2  about 5.9 mole %   NaCl about 4.8 mole %.   
     
     
       8. An assembly as in claim 1 wherein said glass has the composition: Na 2  O  1.5-4.5 mole %   B 2  O 3   92-96 mole %   SiO 2   2.5-4.0 mole %.   
     
     
       9. An assembly as in claim 5 wherein said glass has the composition specified in claim 8. 
     
     
       10. An assembly as in claim 9 wherein said glass has the composition: Na 2  O about 1.9 mole %   B 2  O 3  about 95.2 mole %   SiO 2  about 2.9 mole %.   
     
     
       11. An assembly as in claim 1 in which said glass is in the form of particles and said wall member is porous. 
     
     
       12. An assembly as in claim 1 in which said wall member is a unitary body of said glass and is sealingly engaged with said fibers. 
     
     
       13. An assembly as in claim 9 in which said wall member is a unitary body of said glass and is sealingly engaged with said fibers. 
     
     
       14. An assembly as in claim 10 in which said wall member is a unitary body of said glass and is sealingly engaged with said fibers.